Microsoft Azure SQL Database supports intelligent query processing (IQP), a suite of features permitting a more intelligent and productive query execution. The article aims to illustrate how to configure these features, essential in the context of DP-300 Administering Microsoft Azure SQL Solutions course.
Understanding IQP Fundamentals
IQP provides capabilities that enhance the performance of your workloads automatically without requiring any modifications to your existing applications. These features improve performance by optimizing the most compute-intensive parts of the request processing pipe. Some of the main IQP features include Batch Mode Adaptive Joins, Batch Mode Memory Grant Feedback, Table Variable Deferred Compilation, and Scalar UDF Inlining.
Configuring IQP Features
To use Intelligent Query Processing, you need to run the database compatibility level of SQL Server 2017 (140) or higher. Here are some steps on how to configure the specific IQP feature:
- Batch Mode Adaptive Joins: This feature decides during runtime whether to use a hash join or a nested loop join, based on the actual number of rows. It aids in optimizing join algorithms for a specific query.
ALTER DATABASE SCOPED CONFIGURATION SET BATCH_MODE_ADAPTIVE_JOINS = ON;
- Batch Mode Memory Grant Feedback: Addresses issues related to incorrect query memory grants which can affect performance. This feature continuously learns and adjusts with every subsequent run, helping your workload to achieve consistent performance.
ALTER DATABASE SCOPED CONFIGURATION SET BATCH_MODE_MEMORY_GRANT_FEEDBACK = ON;
- Table Variable Deferred Compilation: Defers the compilation of a table variable until a plan is compiled for a batch, which can improve performance by choosing a plan according to cardinality estimates.
ALTER DATABASE SCOPED CONFIGURATION SET DEFERRED_COMPILATION_TV = ON;
- Scalar UDF Inlining: This feature allows the SQL Server Query optimizer to integrate the logic of scalar UDFs into the calling SQL query, leading to better optimization and improved performance.
ALTER DATABASE SCOPED CONFIGURATION SET SCALAR_UDF_INLINING = ON;
Verifying IQP Feature Status
To verify and check the status of these features, run the following SQL command:
SELECT name, value FROM sys.database_scoped_configurations WHERE name LIKE ‘%BATCH_MODE%’ OR name LIKE ‘%DEFERRED%’ OR name LIKE ‘%SCALAR%’;
This will fetch and display the status of the IQP features configured at the database level.
Impact of IQP on Database Performance
The primary objective of IQP is to improve the query performance automatically without requiring any changes in the existing workloads or applications. From faster processing times to more efficient execution, IQP optimizes your SQL database workloads at their core, giving a significant boost to the overall performance.
In conclusion, IQP dramatically simplifies the process of optimizing the performance of your workloads in Azure SQL Database. Given that all these beneficial features are available at your disposal and how easily they can be configured and utilized, adopting IQP seems an unmissable exercise for all DP-300 Administrating Microsoft Azure SQL Solutions exam candidates.
Practice Test
True or False: Intelligent Query Processing (IQP) is not available for use in the Microsoft Azure SQL Database.
- True
- False
Answer: False
Explanation: IQP is a suite of features available in Azure SQL Database that enhance the performance of SQL database workloads.
True or False: The “automatic tuning” option in Azure SQL Database is a part of the Intelligent Query Processing (IQP) feature.
- True
- False
Answer: True
Explanation: Automatic tuning is a component of IQP in Azure SQL Database that allows the system to adapt and improve your database’s performance over time.
Which of the following are features of Intelligent Query Processing (IQP) in Azure SQL Database? Select all that apply.
- a) Row Mode Memory Grant Feedback
- b) Batch Mode Adaptive Joins
- c) Approximate Count Distinct
- d) Encounter and Resolve Deadlocks
Answer: a) Row Mode Memory Grant Feedback, b) Batch Mode Adaptive Joins, c) Approximate Count Distinct
Explanation: The Encounter and Resolve Deadlocks is not a feature of Intelligent Query Processing (IQP) in Azure SQL Database. The other three options are.
True or False: A query must use batch mode in order to benefit from Intelligent Query Processing (IQP) features in Azure SQL Database
- True
- False
Answer: False
Explanation: Although many IQP features operate in batch mode, some of them, such as Row Mode Memory Grant Feedback, also operate in row mode.
How can you enable Intelligent Query Processing (IQP) for an existing Azure SQL Database?
- a) You cannot enable IQP for an existing database.
- b) By setting the compatibility level of the database to
- c) By turning on automatic tuning in the Azure portal.
- d) By purchasing a premium tier of Azure SQL Database.
Answer: b) By setting the compatibility level of the database to
Explanation: The majority of IQP features are available in Azure SQL Database by setting the database compatibility level to
True or False: Azure SQL Database’s Intelligent Query Processing (IQP) features can help improve your database’s stability and performance.
- True
- False
Answer: True
Explanation: IQP is designed to automatically enhance the performance and stability of SQL queries in Azure SQL Database.
True or False: Scalar UDF Inlining is not part of Intelligent Query Processing (IQP) in Azure SQL Database.
- True
- False
Answer: False
Explanation: Scalar UDF Inlining is indeed a part of IQP and it helps in optimizing the performance of scalar user-defined functions.
Which of the following are benefits of Intelligent Query Processing in Azure SQL Database?
- a) Improved parallelism in execution plans
- b) Improved optimization of join operations
- c) Both a and b
- d) None of the above
Answer: c) Both a and b
Explanation: IQP improves the parallelism in execution plans, optimizes join operations, and provides various other performance enhancements.
True or False: You must individually code each feature of Intelligent Query Processing (IQP) into your SQL queries in Azure SQL Database.
- True
- False
Answer: False
Explanation: The features of IQP are integrated at the server and database levels, eliminating the need for individual code modifications in SQL queries.
How do you disable a specific feature of Intelligent Query Processing (IQP) for a specific query?
- a) You cannot disable IQP features for specific queries.
- b) By using a trace flag.
- c) By setting the compatibility level of the database to below
- d) By turning off automatic tuning in the Azure portal.
Answer: b) By using a trace flag.
Explanation: Trace flags can be utilized to disable specific IQP features for specific queries.
Interview Questions
What is intelligent query processing in Azure SQL Database?
Intelligent query processing in Azure SQL Database is a suite of features that improve the performance, speed, and reliability of your database queries. It optimizes database queries by adjusting their execution based on the workload, data, and computational resources available.
What are the features of Intelligent Query Processing?
The features of Intelligent Query Processing (IQP) include row mode memory grant feedback, batch mode on rowstore, table variable deferred compilation, scalar UDF inlining, approximate query processing and batch mode adaptive joins.
What is the function of the row mode memory grant feedback in Azure SQL Database’s Intelligent Query Processing?
Row mode memory grant feedback recalibrates the memory grant size for a query, ensuring it is neither too big nor too small. A too small grant can cause spills to disk which may slow down query performance, while a too big grant can waste memory and reduce overall system efficiency.
What is the use of the batch mode on rowstore feature in Intelligent Query Processing?
The batch mode on rowstore feature improves the performance of analytical queries that scan large amounts of data. It processes rows in batches instead of a row-by-row basis, leading to improved CPU efficiency.
How does table variable deferred compilation work in Intelligent Query Processing?
Table variable deferred compilation improves plan quality by deferring the compilation of a table variable statement until the first actual execution, at which point, accurate cardinality estimates are available.
What is the purpose of scalar UDF inlining in the context of Intelligent Query Processing?
Scalar UDF inlining automatically transforms scalar UDF, a type of user-defined function, into a relational expression and incorporates it into the calling SQL query. This allows the SQL Server to process the function as inline scalar UDFs, achieving improved performance.
Can you explain the concept of approximate query processing in Intelligent Query Processing?
Approximate query processing allows data professionals to gain insights when real-time data analysis requires statistical relevance rather than complete accuracy. This feature can be useful for queries against large amounts of data where an approximate result is acceptable.
What are batch mode adaptive joins in Intelligent Query Processing?
Batch mode adaptive joins dynamically switch between a hash join and nested loop join during query execution. The adaptive join algorithm uses a threshold to decide at runtime which physical join to use, based on actual row counts, thereby improving query performance.
What is the use of the ‘Interleaved Execution’ feature in Intelligent Query Processing?
Interleaved Execution changes the way SQL Server handles the execution of complex multi-statement table-valued functions. It provides SQL Server with accurate cardinality estimates that result in better-executing query plans.
How are performance improvements identified in Intelligent Query Processing?
Performance improvements are identified through the comparison of query execution times, CPU times, and I/O operations before and after implementing Intelligent Query Processing. Microsoft provides a detailed IQP guide that includes a comparison script for this purpose.
Can you disable a specific feature in Intelligent Query Processing?
Yes, individual features of intelligent query processing can be disabled using the ALTER DATABASE SCOPED CONFIGURATION command. However, disabling them may lead to less optimized query executions.
What is the capacity range for the Azure SQL Database that supports Intelligent Query Processing?
Intelligent Query Processing is currently available for all service tiers of Azure SQL Database starting with the “general purpose” level.
Can query store feature track the performance benefits of Intelligent Query Processing?
Yes, the query store feature tracks query performance over time, which can help in evaluating the benefits of the Intelligent Query Processing feature.
Is Intelligent Query Processing a default feature in Azure SQL Database?
Yes, Intelligent Query Processing is a default feature in Azure SQL Database. It gets automatically applied to all eligible queries without any code changes required.
Can you use Intelligent Query Processing with in-memory OLTP databases?
No, Intelligent Query Processing features are not available with in-memory OLTP databases in Azure SQL. They are geared towards disk-based table workloads.
extutorials.com